By some measures, a total of about 707,000 barrels of oil per day were produced in the United States in 1998 using Enhanced Oil Recovery (EOR) methods, accounting for about 12% of total national crude oil production. Methods vary including thermal (steam and hot water), gas (carbon dioxide, nitrogen), chemical and even microbial enhanced oil production. The carbon dioxide, natural gas and nitrogen EOR consume much more electric power per barrel of oil produced than thermal EOR methods. Current electric power requirements for gas EOR for pumping fluids from the wells (including substantial amounts of water), separating product etc consumes an estimated 1.5 million hp (1,230 MW). Therefore, opportunities are plentiful for business development for petroleum producers and utilities to come up with more effective and less expensive methods of EOR.
Subterranean wells may be drilled primarily to extract fluids such as water, hydrocarbon liquids and hydrocarbon gases. These fluids exist within the earth to depths in excess of 5000 meters below the earth's surface. Subterranean traps, called reservoirs, accumulate the fluids in sufficient quantities to make their recovery economically viable. Whether or not a fluid of interest can reach the earth's surface without aid may be a function of the potential energy of the fluid in the reservoir, reservoir driver mechanisms, reservoir rock characteristics, near wellbore rock characteristics, physical properties of the desired fluid and associated fluids, depth of the reservoir, wellbore configuration, operating conditions of the surface facilities receiving fluids and the stage of the reservoir's depletion.
Many wells in the early stages of production are capable of producing fluids with little more than a pipe to connect the reservoir with surface facilities, as energy from the reservoir and changing fluid characteristics can lift to desired fluids to the surface. However, to improve the economics of a well, it may be necessary to increase the production rate and maximize the recovery of the desired fluid(s) from the well. Transportation of fluids from the reservoir to the surface, that is well bore dynamics, is one of the variables of the well that can be controlled and has a major impact on the economics of a well.
One can improve well bore dynamics by two methods: 1) designing a wellbore configuration that optimizes and improves the flow characteristics of the fluid in the well bore conduit, and/or 2) aiding in lifting the fluid to surface with artificial lift. Artificial lift can significantly improve production early in life of many wells and may be the only option for wells operating in the later stages of depletion. There are numerous systems of artificial lift available and operating throughout the world. The more common systems are reciprocating rod string and plunger pumps, rotating rod strings and progressive cavity pumps, electric submersible multi-stage centrifugal pump, jet pumps, hydraulic pumps and gas lift systems. To fit in the category of artificial lift, additional energy not from the producing formation or fluids input into the well bore is added to help lift fluids in the liquid paths to the earth's surface. With the depletion of the world's fluid reserves, there is a long felt need to develop an artificial lift system and method that is both economical and practical.